Here are seven of the most common errors in livestock fencing, and how to avoid them.
Editor’s note: This article originally appeared in BEEF in March 2009. It has been updated to reflect changes in fence technology and use since then.
3. Correctly sized energizer
Gerrish recommends 1 joule of output per mile of fence, regardless of how many strands of wire. If there’s a total of six miles of fence, it requires a minimum of a 6-joule energizer.
Derynck, who represents Gallagher in Nebraska and the Dakotas, recommends a low-impedance energizer, with a low-amp fuse. “The larger the energizer, the smaller the voltage,” he says, because larger energizers are apt to power through more vegetation and short out. He considers 7,000-8,000 volts high for an energizer.
Grounding is 99% of the electric fence, the specialists explain. Gerrish uses this rule of thumb: 3 feet of ground rods per joule of energizer output. So if the fence is using a 6-joule energizer, 18 feet of ground rods are called for. “Typically this would be three, 6-foot ground rods, spaced at least 10 feet apart,” Gerrish explains.
Gerrish says spacing is key, as a ground rod is essentially an antenna receiving electrons flowing through the soil and back to the energizer, completing the circuit. Ground rods can also interact with a given volume of soil. If three ground rods are driven into the ground 6 inches apart, in essence, they act as one ground rod because of the volume of soil they interact with.
Derynck says most people insert three ground rods near the energizer. He encourages people to space ground rods throughout the whole network of fencing, particularly if the average rainfall of the fenced area is less than ideal for proper grounding.
Galvanized rod is the best for ground rod, and most fencing companies use an insulated galvanized lead-out wire on energizers. “Galvanized isn’t as expensive as copper and you don’t ever have to worry about corrosion,” Derynck says. If there's galvanized wire in the electric fence system, keep everything galvanized. Derynck strictly recommends 12.5-gauge galvanized wire, galvanized ground rods and galvanized connections.
“The most effective place for the ground system is in continuously damp, high-mineral soil,” he adds.
5. Wildlife friendly
Rather than strive for a fence that’s elk and moose-proof, Gerrish suggests a flexible fence. When he moved to Idaho from Missouri, the fencing was high-tensile electric on T-posts, but the T-posts were being bent and insulators broken off due to wildlife. He replaced T-posts with PowerFlex fence posts and has had few problems since, he says.
Another consideration is building a low-profile fence. On Gerrish's 2-wire range fences, the top wire is at 30 inches and the second wire is at 20 inches. It’s designed to allow antelope to go under the wires at a dead run, but low enough that elk will hit the fence with their legs and not the heaviest part of their body.
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